Instrument for indicating the righting-arms and other particulars relating to the stability of ships.



S. B. RALSTO'N. INSTRUMENT FOR INDIGATING' THE RIGHTING ARMS AND OTHERPARTICULARS RELATING TO THE STABILITY OF SHIPS.

APPLICATION FILED M41 21, 1914.

Patented Nov. 3, 1911 2 SHEETS-SHEET 1.

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I ed I C L J 5 0 19" E; 0

1 Z Q E THE NORRIS PETERS COS. FHGWLITHOH WASHINGTON. D. C-

S. B. RALSTON. INSTRUMENT FOR INDIGATING THE RIGHTING ARMS AND OTHERPARTICULARS RELATING TO THE STABILITY OF SHIPS.

APPLICATION TILED MAY 21, 1914. 1,116,119,, Patented Nov. 3, 1914.

2 SHEETS-SHEET 2.

WITNESSES.

THE NORRIS PETERS CO" PHOTULITH-L, WASHINGTON D. C.

Cir

UNITED STATES PATENT OFFICE.

SHIRLEY BROOKS RALSTON, 0F GLASGOW, SCOTLAND.

INSTRUMENT FOR INDICATING THE RIGI-ITING-ARMS AND OTHER PARTICULARSRELATING TO THE STABILITY OF SHIPS.

Specification of Letters Patent.

Patented Nov. 3, 1914:.

Application filed May 21, 1914. Serial No. 840,037.

To all whom it may concern Be it known that I, SHIRLEY BnooKs RAL- STON,a subject of the King of Great Britain, residing at Sandhurst, Balmore,by Torrance, Glasgow, Scotland, have invented a new and usefulInstrument for Indicating the Righting-Arms and other ParticularsRelating to the Stability of Ships, of which the following is aspecification.

This invention relates to an instrument by means of which the rightingarms or levers and other information, contained for a limited number ofconditions of loading of a ship .in the diagram known as curves ofstatical center of buoyancy at different inclinations or angles of heel.This plan of curves is pro vided with a pin or the equivalent, theposition of which indicates that of the center of gravity of the vesseland which can be adjusted to conform to variations of that center at anydisplacement as indicated by variations in the metacentric height or G.M.

The pin or the equivalent has arranged in conjunction with it a bar orother equivalent device which coincides with the vertical or middle linethrough the axis when in the normal position. Means are also providedwhereby a relative movement may be caused to take place between the planof curves and the middle line such that the said bar or the equivalentat all times represents a vertical drawn through the center of gravityof the ship. The bar is furnished with a horizontal scale whereby thelength of the righting arm or the horizontal distance between the centerof gravity and the center of buoyancy usu ally known as G. Z. can beread off on the curve corresponding to any given displacement and forany particular degree of inclination of the ship.

To enable my invention to be fully understood, I will describe it byreference to the accompanying drawings, in which Figure 1 is a plan ofone form of instrument embodying the invention. Fig. 2 is a front viewthereof. Fig. 3 is a side view. Fig. a is a section on the line 4l i,Fig. 1. Fig. is a section on the line 5-5, Fig. 1, and Fig. 6 is a viewsimilar to Fig. l, but showing the parts in a diiferent position.

a is the plan of curves which in the instrument illustrated is in theform of a quadrant which is pivotally mounted at Z) on a sup portingbase member a. The quadrant is graduated in degrees and carries a seriesof curves 0 which indicate for various displacements the horizontaldistances or B. R. between the center of buoyancy of a vessel in theupright position, and the center of buoyancy at the differentinclinations or angles of heel denoted by the graduatio-ns on thequadrant.

d is the pin which is provided upon the quadrant a and which is designedto represent the position of the center of gravity of a vessel. This pin(5 is carried by a bracket 6 which engages with a screw f rotatablymounted in bearings g upon the quadrant, so that it can be turned by themilled head it, but cannot move axially relatively to the said quadrant.As will be obvious, there fore, the rotation of the screw adjusts theposition of the pin cl relatively to the plan of curves upon thequadrant a.

i is the bar which is designed to represent the vertical or middle linethrough the axis when in the normal position, this bar 2' being formedwith a longitudinal slot j with which engages the aforementioned pin (Z.The said bar 71 is provided with brackets 0 in hearings in which isrotatably mounted the pinion rod Z which gears with two racks m and nrigidly mounted on the base a. parallel to one another and to the lowerside of the quadrant or plan of curves when the latter is in the normalposition, shown in Fig. l, in which position the other side of thequadrant is at right angles to the said racks and parallel to the bar2'. As will be obvious by turning the pinion rod Z by either of themilled heads Z it is caused to move along the racks m, n carrying withit the slotted bar 2'. The position of the pin d in the slotted bar 2'can be measured by means of two scales 0 and p, the former of which isattached to the bracket 6 carrying the pin d and with which it moves,and the latter of which is marked upon, or carried by, the side of thequadrant a adjacent to the first scale 0. The scale 0 is divided intofeet and inches and indicates the G. M. or metacentric height, or thedistance of the C. G. from the metacenter. The scale 7) is divided interms of the displacement and represents the heights for varyingdisplacements of the metacenter above the G. B. or the center ofbuoyancy in the upright position of the ship. The two scales combined,therefore, show the height of the C. G: above the C. B. To set thescales 0 and 72 the pin d is adjusted so that its distance from thepivot Z; corresonds to the distance between the center of gravity andthe center of buoyancy of the vessel in the light condition and thescale p is then adjusted so as to bring the G. M. of the vessel in thelight condition and shown on the scale 0 into coincidence with theindication of the light weight of the vessel given on the scale 7),- thesaid scale 7; is then secured to the quadrant a. r

g is the horizontal scale which is secured to the bar a and which isgraduated so as to indicate the length of the righting arm or thehorizontal distance between the center of gravity and the center ofbuoyancy and usually known as G. Z. This scale is set by placing itszero mark against the common origin of the curves 0.

The instrument is employed as follows:- The pin (Z is adjusted by meansof the two scales 0 and 79 so as to represent the particular height ofthe C. G. dealt with. For eX- ample, suppose that the G. M. is four feetand the displacement five thousand tons, then the screw f is turned soas to bring the four foot graduation on the scale 0, into coincidencewith the five thousand graduation on the scale 79, as shown in Fig. 1.The pinion rod Z is then turned so as to cause it to advance along theracks m, this movement also causing the quadrant a to turn upon itspivot so as to represent difierent angles of heel of a vessel. Thisrelative movement of the parts is shown in Fig. 6, in which the screwhas been turned so as to bring the quadrant into such a position thatthe line indicating 20 of heel is in coincidence with the upper face ofthe horizontal scale 9. As will be evident the bar a moves along theracks m, n. parallel to its initial position and consequently representsa perpendicular drop from the C. G. to the horizontal line or B. It.corresponding to the displacement and angle of heel dealt with. Thehorizontal scale g which is attached to the bar then in dicates on theparticular displacement curve 0, in this case the five thousand curve,the horizontal distance in feet of the C, G. from the inclined C. B. orin other words the G. Z. or righting arm.

It will be understood that the embodiment of the invention which isabove particularly described and illustrated in the drawings is given asan example only of the practical application of the invention, theprinciple of which can be applied in other ways.

Claims:

1. An instrument for indicating the righ* ing arms and other particularsrelating to the stability of ships, comprising a supporting base member,a plan of curves plotted to indicate the B. R. for various displacementsof a vessel pivotally mounted on said base member, a pin the position ofwhich indicates the center of gravity of a vessel and which can beadjusted in position relatively to the plan of curves, and a bar for usein conjunction with the pin and means whereby relative movement may beeffected between the plan of curves and the bar such that the latter atall times represents a vertical drawn through the center of gravity ofthe ship, substantially as, and for the purpose, hereinbefore described.

An instrument for indicating the righting arms and other particularsrelating to the stability of ships, comprising a supporting base member,a plan of curves in the form of a graduated quadrant pivotally mountedon said base member, a pin adjustably mounted on the said quadrant, aslotted bar with which the said pin engages, and means for causing thebar to move in a direction parallel with the lower edge of said quadrantwhen said quadrant is in normal position.

8. An instrument for indicating the righting arms and other particularsrelating to the stability of ships, comprising a support ing basemember, a plan of curves plotted to indicate the B. R. for variousdisplacements of a vessel pivotally mounted on said base member, meansfor indicating the center of gravity of the vessel, means forrepresenting a vertical drawn through the center of gravity of the ship,and connecting means whereby relative movement may be effected betweenthe plan of curves and the means for representing the vertical drawnthrough the center of gravity.

4-. An instrument for indicating the right ing arms and otherparticulars relating to the stability of ships, comprising a supportingbase member, a plan of curves plotted to indicate the B. R. for variousdisplacements of a vessel pivotally mounted on said base member, meansfor indicating the center of gravity of the vessel, means for adjustingthe center of gravity means relatively to the plan of curves, means forrepresenting a vertical drawn through the center of gravity of the ship,and connecting means, whereby relative movement may be effected betweenthe plan of curves and the means for representing the vertical drawnthrough the center of gravity.

5. An instrument for indicating the right ing arms and other particularsrelating to the stability of ships, comprising a supporting base member,a plan of curves in the form of a graduated quadrant pivotally mountedon said base member, a pin adjustably mounted on said quadrant, a scaleprovided upon said quadrant and divided in terms of displacement torepresent the heights for varying displacements of the metacenter abovethe G. B. in the upright position of the ship, a scale mounted adjacentsaid pin and movable therewith, said last named scale being divided intofeet and inches to indicate the M, a slotted bar with which the pinengages, and means for causing the bar to move in a direction paraileli'th the lower edge of said quadrant when said quadrant is in normalposition.

6. 1-111 instrument for indicating the righting arms and otherparticulars relating to the stability of ships, comprising a supportingbase member, a plan of curves in the form of a graduated quadrantpivotally mounted on said base member, a displacement scale providedalong one edge of said quadrant, bearings provided on said quadrant, ascrew mounted in said bearings, a bracket provided on said screw, a pinpr0- vided on said bracket, a linear scale also provided on saidbracket, racks provided upon said base member and extending par allel tothe lower edge of said quadrant when in its normal position, a slottedbar mounted for movement along said racks, said pin engaging said slot,and a horizontal scale provided upon said bar and graduated so as toindicate the length of the righting arm.

SHIRLE T BROOKS RALSTON. l'Vitnesses ROBERT G. FRAZER, JIQO. XV.BLAKSTON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. 0.

